Macbook Air power cord problem
anyone have wear problem on macbook air power chords?
MacBook Air, OS X El Capitan (10.11.2), software question
Search the internet or this site – there are many complaints of 'frayed' power cords on Apple products.
Apple Portables: Troubleshooting MagSafe adapters - Apple Support
It seems to be fairly a common issue, some will be replaced by Apple if you take it to them to an Apple Store (your warranty will alter how likely a replacement is). A replacement may also depend on how you have treated the cable – if you wind it up tightly the damage to the cable can be considered your fault though 'misuse'.
Provide more info if that isn't clear, using a damaged cable can be a fire hazard or shock risk if it shorts out.